A projector as an image display device that enlarges and projects various images onto a screen becomes widespread (see, e.g., Japanese Unexamined Patent Application Publication No 2009-199854). More specifically, there are known a projector of the type that projects an image by allowing the light emitted from a light source to transmit through a transmission type image element and a projector of the type that projects an image by allowing the light emitted from a light source to be reflected by a reflection type image element.
If an illumination device is capable of emitting not only light for illumination but also light for image, the illumination device can be used in a wide variety of applications.